"""APScheduler 调度器：FastAPI lifespan 中启动/关闭。"""
import asyncio
import logging
from contextlib import asynccontextmanager
from datetime import datetime
from typing import Optional

from apscheduler.schedulers.asyncio import AsyncIOScheduler
from apscheduler.triggers.cron import CronTrigger

from app.config import get_settings
from app.database import SessionLocal
from app.models.job import Job
from app.models.run import Run
from app.utils.logging import get_logger

log = get_logger(__name__)
settings = get_settings()

_scheduler: Optional[AsyncIOScheduler] = None


async def _execute_scheduled_job(job_id: int) -> None:
    """调度器回调：创建 run 记录并启动执行。"""
    db = SessionLocal()
    try:
        job = db.get(Job, job_id)
        if not job or not job.enabled:
            return
        run = Run(
            job_id=job.id,
            status="pending",
            trigger="scheduled",
            started_at=datetime.utcnow(),
        )
        db.add(run)
        db.commit()
        db.refresh(run)
        run_id = run.id
    finally:
        db.close()

    from app.core.executor import run_backup

    asyncio.create_task(run_backup(run_id, trigger="scheduled"))


def _register_job(job: Job) -> Optional[str]:
    """注册一个 job 的 cron trigger，返回 APScheduler job id。"""
    assert _scheduler is not None
    if not job.enabled or not job.cron_expression:
        return None
    try:
        trigger = CronTrigger.from_crontab(job.cron_expression, timezone=settings.TZ)
    except Exception as e:
        log.error("Invalid cron for job %s: %s", job.name, e)
        return None
    sched_job = _scheduler.add_job(
        _execute_scheduled_job,
        trigger=trigger,
        args=[job.id],
        id=f"job-{job.id}",
        replace_existing=True,
        misfire_grace_time=600,
        coalesce=True,
    )
    log.info("Registered scheduled job: id=%s name=%s cron=%s", job.id, job.name, job.cron_expression)
    return sched_job.id


def _reload_all_jobs() -> None:
    """从 DB 重新加载所有 enabled job。"""
    assert _scheduler is not None
    # 移除现有
    for sj in _scheduler.get_jobs():
        sj.remove()
    db = SessionLocal()
    try:
        jobs = db.query(Job).filter(Job.enabled == True, Job.cron_expression.isnot(None)).all()  # noqa: E712
        for j in jobs:
            _register_job(j)
    finally:
        db.close()


@asynccontextmanager
async def scheduler_lifespan():
    global _scheduler
    _scheduler = AsyncIOScheduler(timezone=settings.TZ)
    _scheduler.start()
    log.info("Scheduler started")
    try:
        _reload_all_jobs()
        yield
    finally:
        _scheduler.shutdown(wait=False)
        log.info("Scheduler stopped")
        _scheduler = None


def reschedule_job(job_id: int) -> None:
    """job 更新后调用此函数重新注册。"""
    if _scheduler is None:
        return
    sched_id = f"job-{job_id}"
    # 移除旧的
    try:
        existing = _scheduler.get_job(sched_id)
        if existing:
            existing.remove()
    except Exception:
        pass
    # 重新加载
    db = SessionLocal()
    try:
        job = db.get(Job, job_id)
        if job:
            _register_job(job)
    finally:
        db.close()


def remove_job(job_id: int) -> None:
    if _scheduler is None:
        return
    try:
        existing = _scheduler.get_job(f"job-{job_id}")
        if existing:
            existing.remove()
    except Exception:
        pass